[coreboot] Convert Assembly JMP to C

Joseph Smith joe at settoplinux.org
Fri Sep 12 02:00:45 CEST 2008

>> mbrs/partition tables
> See how those two don't fit together?
Sorry bad terminoligy MBR/first sector of the Active Partition
>> I really think it is possible to take the data from the
>> mbr/partition table and manipulate it to our advantage, thus
>> bypassing ALL real mode interrupts. The problem would be if an OS
>> (like windows) deciedes to make a INT call....
> You are missing the point.
> If you implement the BIOS method, you will only reach more code that
> requires and assumes a BIOS method. This makes perfect sense;
> The MBR assumes a BIOS is available. Code that the MBR points to
> somehow will also assume a BIOS, because there is no way the computer
> would execute that code unless a BIOS is running and arrived there by
> enumerating MBRs, picking one and going on from there.
>> But for Linux, I really feel it is possible.
> The MBR path will lead to the Linux real mode entry point.
> I hope you agree with me that one major design goal of a new boot
> standard will be to eliminate real mode from x86 boot.
Yes. But I will hope that you will agree with me that a "smart" bootloader
not having to specify a PATH is key.
> Stop wasting time on BIOS things. Do a comparison with all other disk
> labels that the composite of Linux, BSD and Windows NT supports.
I have. 
I got your point. I realize "executing" these "BIOS things" is the wrong
way to go. You would be bound to run into a real mode interrupt. Which you
are really opposed to. But, All the info to boot is laid out in the
MBR/first sector of the Active Partition.

1. the MBR tells us where to find first sector of the Active Partition.
2. The first sector of the Active Partition tells us where OS Boot Sector
code (GRUB stage2) is

Why is that so complicated to see?

Joseph Smith

More information about the coreboot mailing list